This invention relates to an anti-slip device for use in a vehicle occupant restraint belt system having a restraint belt having lap and shoulder belt sections in serial arrangement and a control belt connected to the restraint belt by a "D" ring. The anti-slip device is located at a partitioning point between the lap and shoulder belt sections and is designed to prevent the transfer of the lap belt section toward the shoulder belt section in the event that an accident or other emergency causes the occupant's upper body to lunge forward against the shoulder belt.
In recent years various automatic, passive-type occupant restraining/releasing belt systems have been proposed. It has been found in some passive restraint systems particularly of the type having lap belt and shoulder belt sections that are serially arranged as a continuous restraint belt and in which the restraint belt and the control belt for adjusting the total belt system length are joined with a D-ring, that a part of the belt located at the D-ring slips, permitting an undesirable movement of the lap belt section toward the shoulder belt section. This undesirable movement of the belt in turn permits the upper body of the occupant to move toward the instrument panel, thus increasing the risk of injury.
The applicant has previously proposed anti-slip devices using a spacer member, or a belt support member which is easily broken or deformed during an emergency. These devices are disclosed in Japanese patent applications No. 53-096834 filed July 15, 1978, and No. 53-127044 filed Sept. 18, 1978.